This invention relates to measurement of a polarization vector of an electron beam and to a spin detector capable of detecting simultaneously the magnitude and direction of the polarization vector inside a two-dimensional plane or inside a three-dimensional space.
A spin detector for detecting the direction and magnitude of a polarization vector by using absorption or scattering of a measured electron beam by a target is described, for example, in "Electron Spin Polarization Ratio Detector" (by Koike et al., JP-A-60-178460). According to this method, the trajectory of the measured electron beam incident along the center axis of the detector is once bent and spaced apart from the center axis, and is bent once again and is allowed to be incident into the target plane with a certain angle to the center axis, and is rotated around the center axis in such a manner that this angle of incidence and position of incidence do not change.